/*
 * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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 */

package java.io;

import java.nio.channels.FileChannel;
import sun.nio.ch.FileChannelImpl;


/**
 * A file output stream is an output stream for writing data to a
 * <code>File</code> or to a <code>FileDescriptor</code>. Whether or not
 * a file is available or may be created depends upon the underlying
 * platform.  Some platforms, in particular, allow a file to be opened
 * for writing by only one <tt>FileOutputStream</tt> (or other
 * file-writing object) at a time.  In such situations the constructors in
 * this class will fail if the file involved is already open.
 *
 * <p><code>FileOutputStream</code> is meant for writing streams of raw bytes
 * such as image data. For writing streams of characters, consider using
 * <code>FileWriter</code>.
 *
 * @author Arthur van Hoff
 * @see java.io.File
 * @see java.io.FileDescriptor
 * @see java.io.FileInputStream
 * @see java.nio.file.Files#newOutputStream
 * @since JDK1.0
 */
public class FileOutputStream extends OutputStream {

  /**
   * The system dependent file descriptor.
   */
  private final FileDescriptor fd;

  /**
   * True if the file is opened for append.
   */
  private final boolean append;

  /**
   * The associated channel, initialized lazily.
   */
  private FileChannel channel;

  /**
   * The path of the referenced file
   * (null if the stream is created with a file descriptor)
   */
  private final String path;

  private final Object closeLock = new Object();
  private volatile boolean closed = false;

  /**
   * Creates a file output stream to write to the file with the
   * specified name. A new <code>FileDescriptor</code> object is
   * created to represent this file connection.
   * <p>
   * First, if there is a security manager, its <code>checkWrite</code>
   * method is called with <code>name</code> as its argument.
   * <p>
   * If the file exists but is a directory rather than a regular file, does
   * not exist but cannot be created, or cannot be opened for any other
   * reason then a <code>FileNotFoundException</code> is thrown.
   *
   * @param name the system-dependent filename
   * @throws FileNotFoundException if the file exists but is a directory rather than a regular file,
   * does not exist but cannot be created, or cannot be opened for any other reason
   * @throws SecurityException if a security manager exists and its <code>checkWrite</code> method
   * denies write access to the file.
   * @see java.lang.SecurityManager#checkWrite(java.lang.String)
   */
  public FileOutputStream(String name) throws FileNotFoundException {
    this(name != null ? new File(name) : null, false);
  }

  /**
   * Creates a file output stream to write to the file with the specified
   * name.  If the second argument is <code>true</code>, then
   * bytes will be written to the end of the file rather than the beginning.
   * A new <code>FileDescriptor</code> object is created to represent this
   * file connection.
   * <p>
   * First, if there is a security manager, its <code>checkWrite</code>
   * method is called with <code>name</code> as its argument.
   * <p>
   * If the file exists but is a directory rather than a regular file, does
   * not exist but cannot be created, or cannot be opened for any other
   * reason then a <code>FileNotFoundException</code> is thrown.
   *
   * @param name the system-dependent file name
   * @param append if <code>true</code>, then bytes will be written to the end of the file rather
   * than the beginning
   * @throws FileNotFoundException if the file exists but is a directory rather than a regular file,
   * does not exist but cannot be created, or cannot be opened for any other reason.
   * @throws SecurityException if a security manager exists and its <code>checkWrite</code> method
   * denies write access to the file.
   * @see java.lang.SecurityManager#checkWrite(java.lang.String)
   * @since JDK1.1
   */
  public FileOutputStream(String name, boolean append)
      throws FileNotFoundException {
    this(name != null ? new File(name) : null, append);
  }

  /**
   * Creates a file output stream to write to the file represented by
   * the specified <code>File</code> object. A new
   * <code>FileDescriptor</code> object is created to represent this
   * file connection.
   * <p>
   * First, if there is a security manager, its <code>checkWrite</code>
   * method is called with the path represented by the <code>file</code>
   * argument as its argument.
   * <p>
   * If the file exists but is a directory rather than a regular file, does
   * not exist but cannot be created, or cannot be opened for any other
   * reason then a <code>FileNotFoundException</code> is thrown.
   *
   * @param file the file to be opened for writing.
   * @throws FileNotFoundException if the file exists but is a directory rather than a regular file,
   * does not exist but cannot be created, or cannot be opened for any other reason
   * @throws SecurityException if a security manager exists and its <code>checkWrite</code> method
   * denies write access to the file.
   * @see java.io.File#getPath()
   * @see java.lang.SecurityException
   * @see java.lang.SecurityManager#checkWrite(java.lang.String)
   */
  public FileOutputStream(File file) throws FileNotFoundException {
    this(file, false);
  }

  /**
   * Creates a file output stream to write to the file represented by
   * the specified <code>File</code> object. If the second argument is
   * <code>true</code>, then bytes will be written to the end of the file
   * rather than the beginning. A new <code>FileDescriptor</code> object is
   * created to represent this file connection.
   * <p>
   * First, if there is a security manager, its <code>checkWrite</code>
   * method is called with the path represented by the <code>file</code>
   * argument as its argument.
   * <p>
   * If the file exists but is a directory rather than a regular file, does
   * not exist but cannot be created, or cannot be opened for any other
   * reason then a <code>FileNotFoundException</code> is thrown.
   *
   * @param file the file to be opened for writing.
   * @param append if <code>true</code>, then bytes will be written to the end of the file rather
   * than the beginning
   * @throws FileNotFoundException if the file exists but is a directory rather than a regular file,
   * does not exist but cannot be created, or cannot be opened for any other reason
   * @throws SecurityException if a security manager exists and its <code>checkWrite</code> method
   * denies write access to the file.
   * @see java.io.File#getPath()
   * @see java.lang.SecurityException
   * @see java.lang.SecurityManager#checkWrite(java.lang.String)
   * @since 1.4
   */
  public FileOutputStream(File file, boolean append)
      throws FileNotFoundException {
    String name = (file != null ? file.getPath() : null);
    SecurityManager security = System.getSecurityManager();
    if (security != null) {
      security.checkWrite(name);
    }
    if (name == null) {
      throw new NullPointerException();
    }
    if (file.isInvalid()) {
      throw new FileNotFoundException("Invalid file path");
    }
    this.fd = new FileDescriptor();
    fd.attach(this);
    this.append = append;
    this.path = name;

    open(name, append);
  }

  /**
   * Creates a file output stream to write to the specified file
   * descriptor, which represents an existing connection to an actual
   * file in the file system.
   * <p>
   * First, if there is a security manager, its <code>checkWrite</code>
   * method is called with the file descriptor <code>fdObj</code>
   * argument as its argument.
   * <p>
   * If <code>fdObj</code> is null then a <code>NullPointerException</code>
   * is thrown.
   * <p>
   * This constructor does not throw an exception if <code>fdObj</code>
   * is {@link java.io.FileDescriptor#valid() invalid}.
   * However, if the methods are invoked on the resulting stream to attempt
   * I/O on the stream, an <code>IOException</code> is thrown.
   *
   * @param fdObj the file descriptor to be opened for writing
   * @throws SecurityException if a security manager exists and its <code>checkWrite</code> method
   * denies write access to the file descriptor
   * @see java.lang.SecurityManager#checkWrite(java.io.FileDescriptor)
   */
  public FileOutputStream(FileDescriptor fdObj) {
    SecurityManager security = System.getSecurityManager();
    if (fdObj == null) {
      throw new NullPointerException();
    }
    if (security != null) {
      security.checkWrite(fdObj);
    }
    this.fd = fdObj;
    this.append = false;
    this.path = null;

    fd.attach(this);
  }

  /**
   * Opens a file, with the specified name, for overwriting or appending.
   *
   * @param name name of file to be opened
   * @param append whether the file is to be opened in append mode
   */
  private native void open0(String name, boolean append)
      throws FileNotFoundException;

  // wrap native call to allow instrumentation

  /**
   * Opens a file, with the specified name, for overwriting or appending.
   *
   * @param name name of file to be opened
   * @param append whether the file is to be opened in append mode
   */
  private void open(String name, boolean append)
      throws FileNotFoundException {
    open0(name, append);
  }

  /**
   * Writes the specified byte to this file output stream.
   *
   * @param b the byte to be written.
   * @param append {@code true} if the write operation first advances the position to the end of
   * file
   */
  private native void write(int b, boolean append) throws IOException;

  /**
   * Writes the specified byte to this file output stream. Implements
   * the <code>write</code> method of <code>OutputStream</code>.
   *
   * @param b the byte to be written.
   * @throws IOException if an I/O error occurs.
   */
  public void write(int b) throws IOException {
    write(b, append);
  }

  /**
   * Writes a sub array as a sequence of bytes.
   *
   * @param b the data to be written
   * @param off the start offset in the data
   * @param len the number of bytes that are written
   * @param append {@code true} to first advance the position to the end of file
   * @throws IOException If an I/O error has occurred.
   */
  private native void writeBytes(byte b[], int off, int len, boolean append)
      throws IOException;

  /**
   * Writes <code>b.length</code> bytes from the specified byte array
   * to this file output stream.
   *
   * @param b the data.
   * @throws IOException if an I/O error occurs.
   */
  public void write(byte b[]) throws IOException {
    writeBytes(b, 0, b.length, append);
  }

  /**
   * Writes <code>len</code> bytes from the specified byte array
   * starting at offset <code>off</code> to this file output stream.
   *
   * @param b the data.
   * @param off the start offset in the data.
   * @param len the number of bytes to write.
   * @throws IOException if an I/O error occurs.
   */
  public void write(byte b[], int off, int len) throws IOException {
    writeBytes(b, off, len, append);
  }

  /**
   * Closes this file output stream and releases any system resources
   * associated with this stream. This file output stream may no longer
   * be used for writing bytes.
   *
   * <p> If this stream has an associated channel then the channel is closed
   * as well.
   *
   * @throws IOException if an I/O error occurs.
   * @revised 1.4
   * @spec JSR-51
   */
  public void close() throws IOException {
    synchronized (closeLock) {
      if (closed) {
        return;
      }
      closed = true;
    }

    if (channel != null) {
      channel.close();
    }

    fd.closeAll(new Closeable() {
      public void close() throws IOException {
        close0();
      }
    });
  }

  /**
   * Returns the file descriptor associated with this stream.
   *
   * @return the <code>FileDescriptor</code> object that represents the connection to the file in
   * the file system being used by this <code>FileOutputStream</code> object.
   * @throws IOException if an I/O error occurs.
   * @see java.io.FileDescriptor
   */
  public final FileDescriptor getFD() throws IOException {
    if (fd != null) {
      return fd;
    }
    throw new IOException();
  }

  /**
   * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
   * object associated with this file output stream.
   *
   * <p> The initial {@link java.nio.channels.FileChannel#position()
   * position} of the returned channel will be equal to the
   * number of bytes written to the file so far unless this stream is in
   * append mode, in which case it will be equal to the size of the file.
   * Writing bytes to this stream will increment the channel's position
   * accordingly.  Changing the channel's position, either explicitly or by
   * writing, will change this stream's file position.
   *
   * @return the file channel associated with this file output stream
   * @spec JSR-51
   * @since 1.4
   */
  public FileChannel getChannel() {
    synchronized (this) {
      if (channel == null) {
        channel = FileChannelImpl.open(fd, path, false, true, append, this);
      }
      return channel;
    }
  }

  /**
   * Cleans up the connection to the file, and ensures that the
   * <code>close</code> method of this file output stream is
   * called when there are no more references to this stream.
   *
   * @throws IOException if an I/O error occurs.
   * @see java.io.FileInputStream#close()
   */
  protected void finalize() throws IOException {
    if (fd != null) {
      if (fd == FileDescriptor.out || fd == FileDescriptor.err) {
        flush();
      } else {
                /* if fd is shared, the references in FileDescriptor
                 * will ensure that finalizer is only called when
                 * safe to do so. All references using the fd have
                 * become unreachable. We can call close()
                 */
        close();
      }
    }
  }

  private native void close0() throws IOException;

  private static native void initIDs();

  static {
    initIDs();
  }

}
